Thank you all for the supportive words. I am not planning on helping him find a lawyer and I would like him to tell our son, but if he balks then I will do it. There's no way to hide this from him at this point.
Laying awake at night, here's how I planned on approaching him(or handling him if he approaches me): Tell him that I'm very angry right now and that I don't have anything nice to say nor can I say anything nicely, but that I will get over it and that I just need some time. Then, I will tell him it's his responsibility to figure out how to get the car out of impound, how to get his license suspension worked with, and then find a really good DUI defense attorney. Then, I will tell him that it's his responsibility to do these things and that I have school work to do with our son and that I plan on going to my Al Anon meeting later in the night.
Truly, I am so livid that I really can't talk to him without going off about how he could have killed someone. He was less than 2 miles from home. He could have hit my friends or neighbors and I'm just at my boiling point. It's best for him to handle his own junk right now because anything I do for him will be done resentfully and I will get more angry at myself for stepping in. This is his mess, he has to clean it up.